Fluid pressure booster for sequentially releasing clutch and engaging brake



United States Patent Inventors Roland E. Ilasselbacher Brimfleld;Franklin 0. Koch, J r., Edelstein, Illinois Appl. No. 811,774 Filed 7April 1, 1969 Patented Nov. 17, I970 Assignee Caterpillar Tractor Co.

' Peoria, Illinois a corporation of California FLUID PRESSURE BOOSTERFOR SEQUENTIALLY RELEASING CLUTCH AND ENGAGING BRAKE 7 Claims, 2 DrawingFigs.

U.S. Cl 192/18, 192/9]: 188/264: 192/113 Int. Cl F1611 67/04 FieldofSearch l92/l2.1, 18.], 91A

[56] References Cited UNITED STATES PATENTS 2,564,281 8/1951 Rockwell I192/91AX 2,901,066 8/1959 Garmager..... 192/91AX 3,314,513 4/1967Lakeeialnnnnuu 192/18.1X

FOREIGN PATENTS 765,330 3/1934 France l92/91A Primary Examiner- BenjaminW. Wyche Ill Attorney-Fryer, Tjensvold, Feix, Phillips and LempioABSTRACT: A disc-type, oil-cooled clutch having a servo boost apparatuscontrolled by a plurality of slave cylinders and an operator actuatedmaster control cylinder. Actuation of the master cylinder causes theclutch pressure plates to be disengaged and a clutch brake to be engageddue to a pressurization of a variable-volume chamber between the slavecylinders and the throwout bearing.

Patented Nov. 17, 1910 3,540,557

CYLINDER INVENTORS ROLAND E. HASSELBACHER FRANKLIN O. KOCH, JR.

I BY

f C 4 .[4 7-; 5 2 A TO EYS BACKGROUND AND SUMMARY OF THE. INVENTION Thisinvention relates generally to a hydraulically controlled and boostedflywheel clutch for a bus or truck-type vehicle.

The traditional design for a heavy-duty clutch has normally been a dryface-type pressure plate clutch, which normally proves to be subject torapid wear, over-heating, fading, and in need of adjustment at frequentintervals under normal operating conditions. Currently availablemechanically controlled brakes of this type also make it difficult forthe operator to determine when the rotating parts are stopped forshifting.

Attempts have been made to improve the action of the clutch by usinghydraulically operated pistons which move conventional pressure platelinkages, while stopping the rotating members of the clutch and outputshaft by mechanically operated brakes. Many of these clutches have beenmanufactured with different materials utilized in the clutch discs inexperiments attempting to reduce the wear in the clutch area. Someclutches have been provided with simplified means for making necessaryadjustments from the outside of the housing. A few designs have beenproduced which utilize the rotating inertia of the clutch parts toactivate a spiral thread for boosting the linkage to the clutch.

In spite of all these attempted improvements, the wear problem haspersisted, linkage adjustments still plague service personnel andindustry still requires a design which combines a clutch having longservice life, an arrangement for stopping rotating parts in order toimprove transient gear shifting, cooling and longer life expectancy forthe clutch members, and an operator feel" for the different phases ofclutch and braking operations.

In thisinvention, a disc-type clutch has been designed in one compactand sealed compartment which is continuously cooled by an oil spray andwhich utilizes clutch discs with cork material which, when lubricatedand cooled in this continuous manner. suffer virtually no wear. Whatlittle wear does occur in the clutch package or in the adjoining linkageis automatically compensated for by a change in the volume of hydraulicfluid in thepassages. thus eliminating all need for linkage adjustmentvAs a further feature of the invention, the boosting elements of thedesign are clustered in a compact manner around the It is a furtherobjecthereofto provide such a clutch wherein the discs are lubricatedand cooled in a continuous manner.

It is a still further object of this invention to provide a clutch inwhich any wear occurring is automatically compensated for by meanswithin the clutch.

It is also an object hereof to provide a clutch brake requiring only aminimum of operator exertion.

Other objects and advantagesofthe present invention will become apparentfrom the following description andclaims as illustrated in theaccompanying drawing which, byway of illustration, shows a preferredembodiment of the present inplace at a predetermined position of theoperator's clutch pedal relative to clutch disengagement. Further, theclutch brake is lubricated and cooled by fluid and remains in a readyposition slightly disengaged, and all slack in the linkage path iseliminated.

Thus, the design of the present invention is preferable to the priordesigns because it provides a continuous cooling of all heat-producingparts in a properly sequenced clutch brake which steps all rotatingparts and gives an associated operator feel" of this clutch-to-brakeaction. Also, the invention provides a clutch disengagement throwoutmotion primarily through hydraulic pressure forces as opposed tooperator effort. A clean package is provided with all of the necessarycontrol components located in a remote area and a compact internalarrangement which has long service life without requiring periodicadjustment.

Therefore, it is an object of this invention to provide an improvedclutch with integral booster.

It is also an object hereof to provide such a clutch which does notrequire periodic adjustment.

It is also an object hereof to provide a clutch in which all theheat-producing parts are continuously cooled.

1 It is a further object hereof to provide a properly sequenced clutchbrake which stops all rotating parts.

It is a still'further object of this invention to provide such a clutchbrake which produces an operator feel" for the cessation ofrotation ofthe parts.

It is also an object hereof to provide a clutch brake which iscontinuously cooled by'an oil spray.

vention and principles thereof and what is now considered to be the bestmode contemplated for applying these principles. It is recognized thatother embodiments of the invention utilizing the same or equivalentprinciples may be used, and structural changes may be made as desired bythose skilled in the art, without departing from the present inventionand purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial sectional-schematicillustration of the clutch brake ofthe instant invention; and

FIG. 2 is a view ofa portion of FIG. I, with the brake actuated.

DETAILED DESCRIPTION As shown in FIG. 1, input torque to the inventionis supplied to a torque input means flywheel ll having metal reactionplates 13 thereon. The metal reaction plates 13, which are the firstsection part of a conventional disc-type rotating clutch generallyindicated at 15, transfer the torque, when the clutch is actuated, viacork-faced discs 17 to a second section or clutch hub 19. The clutch hubis mounted by suitable means, such as splines," on the shaft or torqueoutput means 20. Of course, if desired, material other than cork couldbe used on the discs 17.

In normal operation, the plates 13 and discs I7 are engaged in a drivingrelationship by a pressure plate 2! which is biased by a series ofcompression springs or biasing means one of which is shown at 23. Theclutch may be mechanically disengaged by a plurality of throwout levers25 which are mounted so as to pivot on the clutch cover plate 27 atpivot point 29. As the throwout levers 25 are pivoted clockwise aboutpivot 29, the pressure plate 21 is withdrawn from the discs and platesagainst the biasing force of springs 23.

A bell housing 31 serves as an outer envelope for the clutch. brakesystem and also as an intermediate support between the engine and thetransmission. A support 33 is grounded to the right end of the bellhousing and supports a bearing carrier 35, a collar'37, a plurality ofslave cylinders 39 having piston 41 therein, and fluid conduits 43 and45.

The conduit 43 supplies fluid to a variable-volume chamber .47 betweenthe bearing carrier 35 and the collar 37, from a fluid pump source 49.Conduit 45 supplies fluid under pressure from the master brake cylinder48 to the slave cylinders 39.

The support 33 also carries a clutch brake piston 53 having rotationalstops 55. A mating brake surface 57 is situated on the brake piston 53so that, when actuated, it acts upon a second section brake surface 59of the clutch hub 19.

A spring 63 in each of the slave cylinders 39 serves to bias the pistons41 such that collar 37 is positioned as far to the left as possibleduring the normal driving mode. This causes bearing carrier or actuatingmeans 35 to be similarly positioned to the left in a mariner to bedescribed. The pressure of the fluid in chamber 47 causes themaintenance ofa variable-width gap 65 between the collar 37 and bearingcarrier 35. Spring force 63 and pressure in chamber 47 serve to positionthe linkage to insure a "no slack positioning thereof without adverselyaffecting normal engagement of the clutch.

Flow from the chamber 47, through gap 65, is turned by the inner contour67 of collar 37 such that it follows the direction illustrated by arrow69. The fluid then passes the throwout levers 25 to strike the clutchhub web at 71 where, under the influence of centrifugal force, it passesthrough passages 73 in the clutch hub to cool the friction surfaces.

As will be obvious, the forces tending to move bearing earrier 35 andcollar 37 to the left will be balanced at a certain point by the forceof compression springs 23 acting through throwout levers 25.

When master cylinder 48 is actuated by suitable linkage,

pressure will build up in cylinders 39 causing piston 41 to force collar37 to the left, tending to close gap 65. As the pressure in chamber 47builds up, bearing carrier 35 will overcome the force exerted by thecompression springs 23, drawing pressure plate 21 toward the right todisengage the discs and plates.

A further buildup of pressure in slave cylinders 39 causes the bearingcarrier 35 to uncover a plurality of peripherally located slots 81 insupport 33. Fluid in chamber 47 passes through the slots 81 into achamber 83 and acts against a surface 85 ofclutch brake piston 53. Thiscauses the clutch brake piston to move toward the left until brakingsurface 57 contacts the mating surface 59, causing the clutch hub 19 andoutput shaft to stop rotating.

The vehicle transmission is thus prepared for a gear shift. At themoment the carrier 35 uncovers slots 81, the operator will feel anassociated load release at his foot control pedal or other linkage,which indicates that the braking actuation in the clutch is takingplace.

Pressure in the chamber 47 will also cause oil flow through a pluralityof calibrated orifices 89 and passages 91 at a predetermined rate toinsure adequate cooling of the brake surfaces while the brake clutch isapplied.

When the pistons 41 are permitted to move back to the right within theslave cylinders 39, the force of the engaging clutch linkage will moveall of the associated members to the normal position and flow will bedenied to chamber 83, allowing the brake to be released.

Thus the Applicants have provided a new and improved clutch with anintegral booster, which will result in a true advancement of the art dueto its compact design, decrease of part wear, and freedom from therequirement of periodic adjustments. Although a single embodiment hasbeen illustrated and described herein, the scope of the subsequentclaims is such that those skilled in the art may make many alterationsand modifications without exceeding the bounds of the invention as setforth therein.

We claim:

1. in a clutch having a first section mounted on a torque input means, asecond section mounted on a torque output means, and biasing meansmaintaining the first and second sections in operative engagement, abrake surface on the second section, a piston actuatably mountedrelative to the second section and having a mating brake surface forcooperation with the second section brake surface, an actuating meansmounted adjacent the piston. mcanscooperating with the actuating meansfor disengaging the first and second sections.

motivating means for causing the actuating means to actuate pressure onthe piston only after the actuating means has been motivated apredetermined amount. I

2. The clutch of claim 1 wherein the means for allowing the exertion ofa pressure on the piston includes a fluid metering groove which isopened when the actuating means is motivated the predetermined amount.

3. The clutch of claim 2 including means for providing a flow of lluidto the cooperating brake surfaces for cooling them when the piston isactuated.

4. The clutch of claim 1 wherein the motivating means includes a chamberhaving a variable volume and partially bounded by the actuating meansand a movable, operator-actuated means, a variable gap forming a fluidoutlet between the actuating means and the movable means. and means forproviding fluid to the chamber.

5. The clutch of claim 4 including means associated with theoperator-actuated means and the second section for providing a flow offluid to the friction surfaces of the first and second sections forcooling them.

6The clutch ofclaim 4 wherein a metering groove provides a second fluidoutlet from the chamber, the metering groove situated so as to be openedby the actuating means when the 'gap becomes partially closed bymovement of the operator-ad tuated means.

7. The clutch of claim 6 including means in the metering groove forproviding cooling lluid to the brake surfaces when the piston isactuated.

